I'm having some issues with the above combination of settings that is frankly, making me want to scream..

first a little background:

I have a site, lets call it domain1.com , with many members (well into 6 figures), which is being a pita with regards to email.

In the past I had that site on a shared server and 1 group of American ISPs decided they would block all our emails because they didn't like the fact that a large site with so many members was on a shared server with a reverse DNS entry with a different hostname to the domain. Only after I moved the site to its own seperate server with matching hostname and reverse DNS entry did this stop being a problem and they started accepting our emails again. All was well for a year or so until the site owner decided the server bills for that site and several others they own are just too much and we have to condense them all into 1 server again.

Now I have a new decently spec'd server which is easily capable of managing the load, and a dozen sites all moved to it. Some are more important than others, so all the large / important sites got their own dedicated IPs within the server, and the few lesser sites stuck on the main shared IP.

Now in Exim I have selected "Send mail from account’s dedicated IP address" and then made sure that the DNS and rDNS entries for those domains / IPs do correctly match what is set in /etc/mail_reverse_dns

This is where is all comes unstuck, as we are getting rated as "poor" reputation at senderbase.org for the site domain1.com , and some email sent by that site are being bounced/returned with the error "554 Messages sent to this mail system have been rejected due to the bad reputation of the sending mail server " or similar , depending on the recipient ISP.. the message varies slightly but its clear they are all caused by the same poor reputation at senderbase.org

We are not listed on any blacklists.

After more checking using the tools at mxtoolbox.com I find that doing the smtp test throws up the warning "SMTP Reverse DNS Mismatch Warning - Reverse DNS does not match SMTP Banner", and the reason for that is exim replies to an smtp connection with the servers primary hostname, NOT the domain1.com

I'm sure there must be some way to modify the Exim configuration to make it spit out correct domain name, but since cPanel likes to undo such manual changes when software updates I dont really call that a fix (although right now I would take it as better than nothing)

So now my question, have I messed up the configuration / missed a step , or is this just a bug in cPanel exim setup which causes it to give the wrong SMTP banner when using the dedicated IPs setting?

I really need to fix this senderbase issue and resolve the bouncing emails problem, but I am reluctant to contact them and ask for us to be returned to "normal" reputation while there is the slightest issue with our configuration, and it might be that fixing that configuration fixes the issue anyway

I have also recently seen this, where /etc/mailips, /etc/mailhelo and /etc/mail_reverse_dns are all correctly populated, that the mxtoolbox.com test comes back with Warning - Reverse DNS does not match SMTP Banner . While I've not had messages bounced, I have seen them being deferred and subsequently delivered a few hours later.

I'm currently engaged with the support team at buycpanel.com and will post anything of substance as and when / if it comes up.